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Thoracoabdominal asynchrony and ratio of time to peak tidal expiratory flow over total expiratory time in adolescents with cystic fibrosis
Author(s) -
Hunter Janice M.,
Sperry Elizabeth E.,
Ravilly Sophie,
Colin Andrew A.
Publication year - 1999
Publication title -
pediatric pulmonology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.866
H-Index - 106
eISSN - 1099-0496
pISSN - 8755-6863
DOI - 10.1002/(sici)1099-0496(199909)28:3<199::aid-ppul7>3.0.co;2-8
Subject(s) - medicine , cystic fibrosis , cardiology , plethysmograph , spirometry , tidal volume , asthma , airway obstruction , lung volumes , airway , respiratory system , anesthesia , lung
Thoracoabdominal asynchrony (TAA) and the ratio of time to peak tidal expiratory flow over total expiratory time (T ME /T E ) have been used to assess airway obstruction in infants and adults. We obtained these measurements using calibrated respiratory inductance plethysmography (RIP) on 15 adolescents and young adults with cystic fibrosis (CF) and varying disease severity. The measurements were then compared to 15 normal age‐matched controls. TAA was expressed as a phase angle (ϕ) calculated from the abdominal (AB) and ribcage (RC) signals acquired from scalar strip chart recordings. Using CODAS (DATAQ Instruments, Akron, OH) software, the analog signals were digitized, and the differentiated sum (AB + RC) signal was used to calculate T ME /T E . Forced vital capacity (FVC) and forced expiratory volume in 1 sec (FEV 1 ) were obtained using RIP in all subjects. Subjects with CF had a significantly higher mean ϕ than the control subjects (15° vs. 8°, respectively, P = 0.01). In the CF patients the specificity of a high ϕ as an indicator of abnormality was 80%, while the sensitivity was 65%. There was no correlation in the magnitude of ϕ and disease severity as assessed by FVC or FEV 1 . There was no significant difference in T ME /T E between the groups. We conclude that RIP‐acquired ϕ, but not T ME /T E , is a simple and useful method to detect the presence of airway obstructive disease. We speculate that the sensitivity of this method will increase in younger patients with more compliant chest walls and less air trapping. Longitudinal studies of ϕ in infants and young children with lung disease could help in assessing disease severity and progression in this population, in whom repeated measures are few and complex. Pediatr Pulmonol. 1999; 28:199–204. © 1999 Wiley‐Liss, Inc.